1. Field of the Invention
The present invention relates to a remote control system, a remote control apparatus, and a remote control method, which carry out remote control (remote operation) of an electronic apparatus by means of e.g. infrared light, as well as to a program for implementing the method and an electronic apparatus which is remotely controlled. In particular, the present invention relates to a remote control system, a remote control apparatus, and a remote control method, which carry out remote control of an electronic apparatus by sequentially transmitting control signals for providing predetermined control, as well as to a program for implementing the method and an electronic apparatus which is remotely controlled.
2. Description of the Related Art
Conventionally, in a remote control apparatus (hereinafter referred to as “the remote controller”) which remotely controls an electronic apparatus such as a television set or a vide camera by means of infrared light, in the case where, for example, the volume of a television set or the direction of a video camera which captures an image are controlled, the operator continuously depress a control key for controlling the volume or the direction to sequentially transmit control signals to the electronic apparatus so as to sequentially change the volume or the direction, and stops depressing the control key when a desired volume or direction is obtained.
In response to the depression of the control key, the remote controller transmits a light signal (control signal) with a data format in FIG. 21A once. Specifically, FIG. 21A is a view showing a code system in the format of the light signal; reference numeral 301 denotes a leader code. Reference numeral 302 denotes a custom code for identifying e.g. the manufacturer of an electronic apparatus or the model of a set for which the remote controller is used. Reference numeral 303 denotes a parity code; 304, a data code; and 305, an END code which is called a trailer.
FIG. 21B is a view showing a signal waveform applied to a light emitting diode (LED), and for example, the leader code 301 is comprised of a signal present section with a duration of 8T (“T” means the basic time unit of a code), and a signal absent section with a duration of 4T.
On the other hand, if the control key is continuously depressed, the remote controller continuously transmits a repeat code 306 with a format in FIG. 21C at predetermined time intervals of about 100 ms, for example. FIG. 21D is a view showing the signal waveform of the repeat code 306, which is applied to the light emitting diode (LED).
The above-mentioned formats have been disclosed in “Transistor Gijyutsu, November 1996 issue” (CQ Publishing Co., LTD.), and detailed description is therefore omitted.
Also, Japanese Laid-Open Patent Publication No. H08-163531 has disclosed a technique for controlling a VTR via a CATV using a remote controller therefor in a system which controls the VTR by means of an infrared control unit attached to the CATV.
This publication discloses an arrangement that a control signal is transmitted via a remote controller, (light), CATV, (cable), the infrared control unit, (light), and the VTR in this order, and to prevent abnormal reception due to collision of light from the remote controller and light from the infrared control unit, the publication further discloses a technique according to which a control signal is transmitted only immediately after a key of the remote controller is depressed, and immediately upon receiving the control signal, the infrared control unit transmits a control signal to the VTR, and a technique according to which a control signal is transmitted immediately after a key of the remote controller is depressed, and a control signal is again transmitted when the key ceases to be depressed, and while the remote controller transmits no control signal, the infrared control unit transmits a control signal to the VTR.
The above-mentioned repeat code 306, however, is only indicative of “the same as before”, and therefore, in the case where an electronic apparatus as an apparatus to be controlled fails to receive the initial data (leader code 301), what kind of instructed operation should be executed cannot be recognized, and thereafter, even if the repeat code 306 is transmitted, the electronic apparatus only has to make the repeat code 306 through.
Further, according to the techniques disclosed in Japanese Laid-Open Patent Publication No. H08-163531, a signal is transmitted from the remote controller only once or twice, and hence the CATV can fail to receive an infrared light signal with a high possibility, and the same problem arises as in the case where the repeat code 306 is used.
In either case, the operator of the remote controller misbelieves that the remote controller or the apparatus to be controlled has failed since the apparatus to be controlled does not operate in response to the depression of a key, or misbelieves that an intended key of the remote controller has not yet been turned on, and therefore continuously depresses the key with an excessive force, and therefore the remoter controller is not easy to use.
There has been known a remote controller which repeatedly transmits the same control signal during the depression of a key, and this remote controller can solve the above described problems since the same control signal as the previous one is repeatedly transmitted even if an apparatus to be controlled has failed to receive the first signal.
However, in the case of a key such as a channel switch key for a TV set or a video signal input switch key other than a key used for e.g. volume control which requires an instruction for continuous operation, a control signal is continuously transmitted although the control signal does not have to be repeatedly transmitted even if the key is continuously depressed (this also applies to the case where the repeat code 306 is transmitted), and this wastes a battery for the remote controller.
Here, in the case where the key is slowly depressed once, the key is usually depressed for several 100 ms, but the transmission of one signal is completed in several 10 ms. Therefore, when the key is depressed, a control signal is unconsciously transmitted about four or five times. Thus, even if the operator tries to prevent the waste of battery for the remote controller by consciously decreasing the period of time for which the key is depressed, there is a limit.
To address this problem, it can be envisaged that a control signal is transmitted only once even if a key which does not require an instruction for continued operation is continuously depressed.
In this case, however, since one signal is transmitted for only a short period of time, i.e. about several 10 ms as described above, the apparatus to be controlled can fail to receive a control signal with a high possibility in the environment where there are a large amount of fluorescent light of a fluorescent lamp or other disturbance light. In this case, as described above, the operator of the remote controller misbelieves that the remote controller or the apparatus to be controlled has failed since the apparatus to be controlled does not operate in response to the depression of the key, or misbelieves that an intended key switch for the remote controller has not yet been turned on, and therefore, should continuously depress the key with an excessive force. Therefore, the remote controller is not easy to use.
Further, in the case of the remote controller which repeatedly transmits the same control signal during the depression of a key, if the reception of a control signal is interrupted by an obstacle or the like during the depression of a key, and then the obstacle or the like is removed to receive the next control signal, the apparatus to be controlled determines that the key has been released once and then depressed again, and hence numeric values indicative of times or the like are redundantly set.